The present invention relates to a power distributor and a memory device having the same. The power distributor in accordance with an embodiment of the present invention can be applied to other semiconductor integrated circuits.
Lately, a typical semiconductor device including a dynamic random access memory (DRAM) has been required to operate with a low voltage and at a high speed. If a memory is driven with a low voltage at a high speed, the memory may have the following unintended consequences. That is, when the memory operates at a high speed, small inductance of a package or a board may disturb supplying necessary power. If a memory is driven with a low supply voltage in order to reduce power consumption thereof, the noise of a low power supply voltage may change circuit delay, and cause the memory to erroneously operate.
In order to overcome such consequences, a reduction in the noise of low power supply voltage is desired. That is, impendence between an external power supply and an on-chip circuit is desired to be controlled to be small. For example, the impedance may be reduced by increasing the capacitance of a reservoir capacitor at a peripheral circuit in a chip. Here, the reservoir capacitor may be used in a power distributor to minimize a voltage drop due to power consumption.
Although it is possible to obtain small impedance by using a reservoir capacitor having a small equivalent series resistance (ESR) with respect to radio frequency noise, a reservoir capacitor having very high capacitance may be required for compensating low frequency noise.
Meanwhile, the capacitance of a reservoir capacitor is in proportion to a surface area of an electrode and in inverse proportion to a thickness of a dielectric. Therefore, a thickness of a dielectric must be thin to obtain large capacitance in a given area. However, leakage current of the reservoir capacitor becomes a significant problem if the dielectric is thin.